Power supply controllers have been provided in which a semiconductor switching element for high power, for example a power MOSFET, is provided on a conduction channel between a power source and a load, and power supply to the load is controlled by turning on and off the switching element. Such power supply controllers having a self protection function are known. The self protection function controls the electric potential of a control terminal of the switching element and turns off the switching element if an overcurrent flows through the conduction channel, thereby protecting the switching element itself. Specifically, in a self protection function, such as the one described in Japanese Patent Laid-Open No. 2001-217696, a current detecting resistor is connected with a load terminal (for example the source or drain of a MOSFET) in series, a load current flowing through the switching element is detected on the basis of a voltage drop at a resistor and, if the load current exceeds a predetermined threshold, it is determined that an overcurrent has occurred. An electric current shutoff based on the self-protection function is designed in such a manner that the switching element automatically returns to the on state on expiration of a predetermined after shutoff time period. This is because this function is provided in order to avoid overheat of the switching element itself, and as such, a heat sink provided for that purpose quickly decrease the temperature of the switching element after the abnormal current is shut off.